Insight into the engine performance of pyro-oil synthesized through catalytic co-pyrolysis of mixed waste plastics in the presence of dolomite modified with silica and ZSM-5

Abstract

The production of hydrocarbon-rich liquid fuels from mixed waste plastics through the catalytic pyrolysis process is reported including engine performance. Four different catalysts, viz., DOL, SiDOL, ZSM-5, and ZSMDOL, were prepared and characterized using XRD, FTIR, FE-SEM, and EDX. The catalytic activity was assessed in pyrolysis process to produce pyro-oils. The fuel properties were determined using various ASTM methods. The analysis showed that catalysts can change fuel properties such as viscosity, density, cloud & pour points, flash & fire points, calorific values, etc. The GC–MS results suggested a higher fraction (66–85%) of lower hydrocarbons (<C12) are formed during catalytic cracking as compared to thermal cracking (∼51%). FTIR and NMR analysis confirmed the presence of different hydrocarbons (paraffin, olefin, and aromatics) in pyro-oils. A higher percentage of aromatic hydrocarbons was seen with ZSM-5 catalyst due to diffusion of primary pyrolysis products into catalyst pores resulting in formation of aromatics via a common hydrocarbon pool and higher H/C value in the feedstock. Engine performance test with 10% pyro-oil blending enhanced the brake-thermal efficiency by 1.01–10% and reduces brake-specific fuel consumption by 8.72–10.1%. On the other hand, CO emission was reduced by 40.4%, 20%, 16.1%, 8.9%, and 6.2% when commercial diesel was blended with PO-NC, PO-DOL, PO-SiDOL, PO-ZSM, and PO-ZSMDOL, respectively. Similarly, the emissions of HC and NOx were reduced by 61% and 10.85%, respectively, when the pyro-oil blend was used. Approx. 54% reduction in carbon residue was also achieved in the case of catalytic pyro-oils blended fuel sample.